one (1) piece A3 paper (the thinner the better, thin newspaper works really well)
one (1) sheet sticky back plastic about 36 cm * 24 cm (you can use tape but its far more fiddley)
one (1) small sharp craft knife.
NO ruler needed (after measuring out the sticky back plastic anyway)
A little folding skill

Step 1: First Folds

1, Fold the paper into half and half again and open back out both horizontally and vertically. this will give you 16 equal rectangles.
Then, fold a 'lip' at the top edge about 1-2 cm down

Step 2: Making the pockets

1, fold the paper with the to edge folded towards you as shown from the center top down to the left middle, and then to the right middle on the other side so it is symmetrical.

2, turn the paper over and fold the top point down so that it touches the middle. Turn the paper back over and it should look like picture 3

Step 3: Second pocket

colour change!! (didnt have yellow at home...)

1, where there are already creases, fold the sides into the middle, then open it out completly, like so...

2, so you can see everything inside. If you want to now it would be a good time to fold the bottom 1/4 backwards with the crease already made so that you dont have to undo everything later. When you fold the front sides back again, bring the parts that look like lapels out...